STERLING, Va. – Most days, a weather forecast is taken for granted. But on some days, like Thursday, it’s about more than just an umbrella.

At the National Weather Service center in Sterling, Va., dangerous weather is just part of the job for 28 employees. While local forecasters see some of the same information as the NWS, much of it originates at these offices.

“When you have that life-threatening situation, you want to have one source of that information,” says Chris Strong, a coordinator.

But computer models, sensors and observation only go so far. Strong says weather forecasting still relies on a lot of interpretation, which can get dicey throughout a long, hot summer, when things tend to change quickly.

“The La Plata tornado – that was one of the strongest tornadoes we’ve had here,” says Strong. “Back in the early 2000s, (it) formed as soon as it got to the Potomac River interaction and then dropped right as it got into Charles County, Md.”

Even with rapidly changing summer storms, Strong says winter storms can actually be more difficult to predict.

WTOP’s Hank Silverberg contributed to this report. Follow @hsilverbergWTOP and @WTOP on Twitter.